Experimental analysis of statistical properties of underwater channel in a very shallow water using narrow and broadband signals

Time-varying environment makes it difficult to describe channel impulse responses in the ocean. Therefore, statistical approach has been tried to characterize propagation channel especially for high frequency. Although theoretical analysis proves that probability density function(PDF) of received signal may have Rayleigh or Rician distribution, it is hard to assure that complicated ocean channel has the same distribution all the time. In this paper statistical properties of shallow water channel is analyzed based on measured data at a sea trial. The data is gathered by transmitting pure tone and broadband sound with changing frequency components as well as transmitter location. Omni-directional transducers are used for both the transmitter and receiver. The results of pure tone signal show that PDF can be fitted as Rayleigh or Rician distribution and statistical parameters are dependent on frequency and range. Analysis of broadband signals verifies that each propagation path has its own statistical properties.